Drilling apparatus



'W. W. PAGET DRILLING APPARATUS Filed April 19, 1939 Jime so, 1942.

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Patented June 30, 1942 namlmo APPARATUS Win W. Paget, Michigan City, Indz, assiguor to Sullivan Machinery Company, a corporation of Massachusetts Application April 19, 1939, Serial No. 268,792

33 Claims.

My invention relates to the field of drilling, and more particularly to the field of hard rock drilling, but not exclusively thereto. It comprises improvements in drilling apparatus of the high speed type, and improvements in drill rotating, cleaning, feeding, and controlling structure.

In the drilling of the harder rocks it is very desirable to reduce the amount of rock actually cut away, and so core-type drilling, if it can be made rapid enough, is very desirable. By the use of impregnated bits-bits with numerous small diamonds or pieces of borts bedded or set in a suitable matrixbits which can be made in the form of relatively thin annuli can be produced; and if the rotation speed is made much greater than the usual core drilling speeds, and the pressure for feeding is made high, yet not high enough to cause deformation of or burning of the bits, and if cooling and cleansing liquid supply in adequate quantity at all times can be assured, and if suitable simple means be made available for the breaking loose and removal of the cylinders of rock out free laterally from the surrounding bed, exceedingly rapid hole formation, even in very hard rock, is possible.

In rotary core drills utilizing annular bits impregnated with carbon cutting elements, or socalled diamond core bits, it has been noted during the development of this invention that the drilling speed may be considerably increased if the drill bit is rotated at extremely high speeds materially above the normal core drilling speeds and a suitable feeding pressure is applied to the drill bits. It has also been found that when the drill bit is rotating at such high speeds it must be protected automatically from the application of an excessive feeding pressure, and the flow of drilling fluid to the bit must be constantly maintained or the drill bit will become damaged due to excessive heat caused by friction and abrasion. Moreover, it is exceedingly important that the bit be not withdrawn from the hole while rotating at the high speed which is desirable during drilling.

An object of this invention is to provide an improved drilling apparatus of the high speed, rotary, preferably but not necessarily core type, which will enable the drill bit to be rotated at anextremely high speed while absolutely precluding the possibility of the bit becoming damaged due to an excessive feeding pressure, or the failure of the drilling fluid supply to the bit. Another object is to provide an improved drilling apparatus of the high speed, rotary, preferably but not necessarily core type, having improved means for rotating the drill bit and for controlling drill bit rotation. A further object is to provide an improved rotary drilling apparatus having improved feeding means for the drill bit and improved means for regulating the feeding means. Still another object is to provide, in a drilling apparatus of the above character, an improved hydraulic feeding means and means controlled automatically by resistance to rotation of the drill bit, for controlling the feeding pressure. A still further object is to provide improved means for rotating the drill bit and having associated therewith improved means associated with the hydraulic feeding means for controlling said bit rotation means. Yet another object is to provide improved bit rotation means embodying a rotary motor for efiecting bit rotation and having associated therewith improved controlling means for starting and stopping said motor, controlled automatically by the controlling means for the feeding means. Another object is to provide an improved drilling apparatus of the high speed, rotary, preferably but not necessarily core type, having improved means for automatically controlling the feed of the bit so as to maintain an automatically controlled supply. A further object is to provide a novel supporting and guiding structure for the drill and embodying means whereby the drill may be swung laterally on its mounting means to move the same into a position at one side of the drill hole. Yet another object is to provide an improved hydraulic feeding means having manual feeding means associated therewith in an improved manner. These and other objects and advantages of the invention will, however, hereinafter more fully appear.

In the accompanying drawings there is shown for purposes of illustration one form which the invention may assume in practice.

In these drawings:

Fig. 1 is a side elevational view of the improved drilling apparatus, showing the feed cylinder in its retracted position.

Fig. 2 is a view similar to Fig. 1, with parts shown in longitudinal vertical section, showing the feed cylinder in its extended position.

Fig. 3 is an enlarged front and elevational view of the drilling apparatus shown in Fig. 1.

Fig. 4 is an enlarged rear end elevational view of the drilling apparatus.

Fig. 5 is an enlarged cross sectional view taken substantially on line 5-6 of Fig. 2.

Figs. 6 and '7, when taken together, constitute a view in longitudinal vertical section through the improved-drilling apparatus.

Fig. 6 is an enlarged detail sectional view taken in the plane of Fig. 6 and on the line 8-6 of Fig. 9.

Fig. 9 is an enlarged cross sectional view taken substantially on line 9-9 of Fig. 6.

Fig. 10 is a horizontal sectional view taken substantially on line Ill-I0 of Fig. 8.

Fig. 11 is a fragmentary sectional view taken in the plane of Fig. 8, with the feed control valve and valve bushing omitted, illustrating the fluid passages associated with the feed control valve.

Fig. 12 is a cross sectional view taken on line l2-i2 of Fig. 10.

Fig. 13 is a cross sectional view taken on line l3-l3 of Fig.10.

Fig. 14 is a sectional view, with parts shown in elevation, taken in the plane of Fig. 6, showing the drilling motor and feed cylinder in partially extended positions.

Figs. 15 and 16 are fragmentary sectional views taken in the plane of Fig. 8, showing the feed control valve in different positions.

Fig. 17 is a cross sectional view taken on line IT-ll of Fig. 15.

Fig. 18 is a cross sectional view taken on line 16-16 of Fi 16.

Fig. 19 is a cross sectional view taken on line l9-l9 of Fig. 15.

Fig. 20 is an enlarged cross sectional view taken substantially on line 20-23 of Fig. 6.

Fig. 21 is a vertical sectional view takensubstantially on line 2I-2l of Fig. 20.

Fig. 22 is a cross sectional view taken substantially on line 22-22 of Fig. 21.

Fig. 23 is a detail sectional view taken on line 23-23 of Fig. 20.

Fig. 24 is a detail sectional view taken on line 24-24 of Fig. 22.

Fig. 25 is a cross sectional view taken substantially on line 25-25 of Fig. 26.

Fig. 26 is a view in longitudinal section taken substantially on line 26-26 of Fig. 25.

Fig. 27 is a vertical sectional view taken substantially on line 21-21 of Fig. 20.

Fig. 28 is a longitudinal sectional view taken substantially on line 23-28 of Fig. 25.

Fig. 29 is a detail view in longitudinal section taken substantially on line 29-29 of Fig. 25.

Fig. 30 is a longitudinal sectional view taken through the core bit and barrel.

Fig. 31 is a front end elevational view of the core drill bit.

Fig. 32 is a longitudinal sectional view taken through the' improved core breaker.

Fig. 33 is a front end elevational view of the core breaker shown in Fig. 32.

Fig. 34 is a diagrammatic view illustrating the hydraulic fluid system.

In this illustrative embodiment of the invention there is disclosed an improved drilling apparatus of the high speed, rotary type adapted for use at will with core type or plug type bits and generally comprising drill bit rotation means, generally designated 1, drill bit feeding means, generally designated 2, and drill guiding and supporting means generally designated 3.

The primary drill supporting and guiding means .The drill supporting and guiding means 3 pmprises a trunnion member 4 having a swivel plate 5 adapted to be clamped in the saddle mounting of a mme column or any other suitable support. The trunnion member 4 has a longitudinally extending bore which receives a cylindrio tube 6, the latter fixed at its ends within a support member I, the latter in turn having a longitudinally extending bore which slidingly receives and guides the feed cylinder 6 of the hydraulic feedmg means. The tube 6 provides a swivel mounting for the support member I so that the drill may be tilted laterally to one side or the other, thereby to move the drill into a position at one side of the drill hole, for a purpose to be later explained. The support member 7 carries dirt seals 9, 9 at its opposite ends, and these seals sealingly engage the exterior surface of the feed cylinder 8, thereby to prevent access of dirt or other foreign matter to the cylinder guide bore.

As shown in Fig. 7, a plunger lock 12 is insertible in a locking aperture l3 formed in the member 4 for locking the support member 1 in its upright position as shown in Fig. 5. This plunger lock is guided within bores formed within a depending lug I4 integral with the support member 1, and a coil spring l5 constantly urges the plunger lock toward its innermost locking position. A handle I6 is secured to the plunger lock whereby the locking portion thereof may be manually released from the locking aperture against the tension of the coil spring IS.

The hydraulic feed cylinder and piston structures The feed cylinder 3 of the feeding means 2 contains a reciprocable feed piston l1 having a tubular piston rod I8 fixed at its forward end at 19 to a head plate or front piston flange 20 (Fig. 6). The feed piston comprises an inner member 2| (Fig. 7) having a flanged plate 22 secured, as by screws to the rear end thereof. An annulus or ring-like washer 23 is seated against a shoulder at the forward end of the inner member 2|, while a similar annulus 24 abuts the front face of a bushing 25, the latter in turn abutting at its rear face the flange of the plate 22. Arranged between the end annuli 23, 24 and a. centrally located annulus 26 and surrounding the body of the inner member 2| are spacing sleeves 21, 21. Mounted on these sleeves and disposed at the opposite sides of the centrally located annulus are packings 23, 28, and interposed between these packin s and the end annuli 23, 24 are coil springs 29 for constantly maintaining the packings in tight sealing engagement with the walls of the bore of the feed cylinder 8.

The feed cylinder 8 has front and rear heads 30 and 31, the former carrying a packing 32 sealingly engaging the exterior periphery of the piston rod and the latter head being detachably secured, as by screws, to the rear end of the feed cylinder. The front cylinder head consists of a member 33 surrounding the forward end portion of'the feed cylinder and abutting at its rear face a flange 34 integral with the feed cylinder. A detachable end plate 35 abuts the front face of the member 33. The packing 32 is contained in a removable sleeve 36 fitting the cylinder bore and is arranged between an inwardly directed flange 31 on the sleeve and a coil spring 38, the latter engaging a split ring 39 seated in an internal annular groove in the sleeve. This coil spring always maintains the packing 32 in tight sealing engagement with the cooperating parts. The sleeve 38 has at its forward end an external annular flange abutting the forward end of the feed cylinder, as shown in Fig. 14. Arranged between the plate 35 and this sleeve flan e is a dirt seal 49 seallngly engaging the exterior surface of the feed piston rod. Interposed between the flange 31 and the seal 49 and surrounding the piston rod is a bushing.

The feed cylinder feeding and adjusting means The front and rear feed cylinder heads 39 and 3| have depending bosses provided with bores in which is rotatably mounted a cylindrical tube 4| extending centrally through the pivot tube 6 and having formed along a portion of the length thereof screw threads 42 coacting with the threads of a nonrotatable feed nut 43 secured at 44 within the support I. The forward end of the tube H is fixed against axial displacement with respect to the feed cylinder by a split ring 45 seated in external and internal grooves v on the tube 4| and a detachable end plate 46 respectively, the latter secured to the front head member 33 as shown in Figs. 6 and 14. The tube 4| projects rearwardly through the rear head boss, as shown in Fig. 7, and has secured thereto a handle 41 having a grasping portion 48. This grasping portion is fixed to a spring-pressed plunger lock 49 engageable with a locking projection 50 integral with the rear cylinder head 3|, and this lock holds the feed screw tube 4| against rotation during. automatic feeding of the drill.

As above mentioned, the forward end of the feed piston rod I8 is secured at H! to and supports the head plate or front piston flange (Fig. 6). Secured, as by screws, to the plate 29 is a control head 5|, and fixed at 52 Within a laterally located bore in the control head is a tube 53, the latter extending centrally in telescopic relation within the feed screw tube 4|, in the manner shown. The tube 53 has a sliding fit with the walls of the tube 4| and serves to maintain the feed cylinder against rotation within its bore on the support 1, and in efiect acts as a lateral sliding guide for the drill.

The drill bit driving motor and its mounting The drill bit rotating means I comprises a rotary motor 54, herein a high speed electric motor of the totally enclosed type comprising a cylindric motor casing 55 provided with front and rear heads 56 and 51, the motor parts being held in assembled relation by tie bolts 58. The motor has a usual field 59 and an armature rotor 60, the shaft 6| of the rotor being supported inboarings suitably journaled in the motor heads. Surrounding the eylindric motor casing 55 and in eifect providing an outer casing, is a. cylindric shell 52 fitting cylindric portions of the motor heads and held between shoulders on the heads by the tie bolts, and this outer shell cooperates with the inner casing to provide an annular space 63 surrounding the inner motor casing. The tie rods extend longitudinally through this space in the manner shown in Fig. 6. Arranged in a housing 84 secured to the front motor head is a circulating fan 85 for cooling air, this fan being keyed to the motor rotor shaft and acting to draw cooling air through radial passages 65 in the rearward portion of the outer shell 62, through the annular space 63 between the tie bolts and through passages 61 in the front motor head, the cooling air discharging from the motor casing outwardly through radial discharge passages 68 formed in the fan housing 54. The rear motor head 51 has a rearward cylindric projection 69 mounted for limited rotation in ball bearings 19 supported within a bore formed in the control head 5|. The bearings are retained in the control head bore by means of a retaining annulus or ring 1| secured, as by screws, to the control head, and the cylindric projection is held against axial displacement with respect to the bearings by means of an end plate 12 secured, as by screws, to the projection 69. A dirt seal 13 is arranged within the control head bore and sealingly engages the exterior periphery of the end plate 12. As shown in Fig. 6, the end plate 12 has a cylindric portion fitting the bore in the cylindric projection 89 of the rear motor head, and the cylindric end plate portion carries sealing rings 14 for sealingly engaging the bore, to prevent leakage between the parts. The purpose of the rotary mounting for the motor will be later explained.

Threadedly secured at 15 to the forward end of the motor rotor shaft is an adaptor nut 16 to which is connectible the supporting means for the drilling implement, or the rod line that supports the latter when the hole is deeper. Electric energy may be conducted to the motor 54 from any convenient source through a conventional connector plug I! mounted on the control head 5| and connected through wiring 18 to the motor, and a switch 19 is provided for effecting starting and stopping of the motor, this switch being arranged in a chamber 8|) formed within the control head 5|, in the manner shown in Fig. 6.

Manual control for hydraulic feed Now referring to the means for supplying liquid under pressure to the hydraulic feeding means, it will be noted that formed in the control head 5| is a liquid supply chamber 8| having a usual liquid supply connection 82 connected to any convenient source of liquid pressure supply, and arranged in this chamber is a strainer 83 through which the liquid flows from the supply connection 82 to the chamber space surrounding the strainer. Formed in the control head 5| is a longitudinal bore receiving a valve bushing 84 in which is slidably mounted a feed control valve 85. This valve is of the sliding spool ty e and has its stem 86 connected by a coupling and guiding collar 81 to a valve adjusting screw 88, the threads of the latter engaging threads formed within the tube 53, so that when the screw 88 is rotated the valve is moved axially within the bore of the valve bushing. The screw 88 is -s-ecured at 89 to a tube 99, this tube extending centrally within the tube 53 and being square in cross section and having telescopically fitted within its square bore a square control red; at. This rod is secured at its rear end, as shown Fig. '7, to a cylindric portion 92 rotatably mounted within the bore of the tube AI and having secured thereto a control knob 93 located in adjacency to the feed screw handle 41. Itis accordingly evident that, irrespective of the posi-' tion of the feed cylinder within its bore in thesupport I, the spool valve may be operated through the telescopic connections by the control knob 98.

The'spool valve 85, as shown in Fig. 8, has narrow lend spools and a somewhat wider intermediate spool, and a wide annular groove 95 separates the intermediate spool from the rear end spool, and a narrow annular groove 95 separates the front end spool from the intermediate spool. The valve bushing 84 has three transverse bottom slots 91, 98 and 99 and a transverse top slot I00, and the slot 9'5 communicates with the liquid supply chamber 8|, and the slots 98 and 99 respectively communicate with grooves WI and I02. The top slot I communicates with a groove I93. At the front end of the valve bushing is a groove I04 connected by a transverse passage I to atmosphere (see Fig. 19), and a groove I06 at the rear end of the valve, bushing is connected, through longitudinal passages I01 (Fig. 11) in the'walls of the bore receiving the valve bushing, with the exhaust groove I04. The valve has an axial end bore I08 closed at its front end by a suitable plug; and a series of radial ports I09 connect the bore I08 with the wide groove 95 and a similar 'series of radial ports I I0 connect the bore I08 with the narrow groove 98. (See Figs. 15 and 17.) The groove I03 is connected through passages III,.II2 and H3, respectively, formed in the control head 5|, a member II4 clamped between the control head 5| and the end plate 20, and the end plate 20, with the interior of the piston rod I8; and a port II5 (Fig. 7) connects the piston rod bore with the feed cylinder bore at the front side of the feed piston II. As shown in Fig. 6, the member I I4 projects forwardly within the control head chamber 80, and the motor switch I9 arranged in the chamber 80 is carried by the member II4. Liquid under pressure may be supplied to the rear end of the feed cylinder 8, at the rear side of the feed piston, through a passage II5 (Figs. 10 and 21) communicating with the groove IN and a passage I I I, past a torque controlled valve means, generally designated I I8, to a passage H9. The passage I I9 communicates with a passage I20 in the member H4, and a passage I2I in the end plate 20 (Fig. 29) connects the passage I20 with a recess I22. The recess I22 is connected by a liquid conducting tube I23 extending centrally rearwardly through the feed piston rod, with the rear end of the feed cylinder bore at the rear side of the feed piston. As shown in Fig. '7, the feed piston II carries a packing I24 sealingly engaging the exterior surface of the tube I23, and a gland plug I25 is provided for adjusting this packing. When the feed piston I1 is in its rearmost position in the feed cylinder, as shown in Fig, 7, the tube I23 communicates with a cavity I28 in the rear cylinder head 3I, this cavity opening forwardly directly within the feed cylinder bore. It will thus be seen that, depending upon the position of the slide valve 85, liquid under pressure may flow through the slot I00 in the valve bushing and the reverse feed passages above described, to the front end of the feed cylinder here, or through the valve passages and through the forward feed passages above described, to the rear end of the feed cylinder bore.

Coordinated hydraulic motor control comprises a diaphragm I30 (Fig. 6) clamped, as

shown most clearly in Fig. 29, between the end plate 29 and the member IIQ, the adjacent iaces of these members being recessed to provide a diaphragm chamber therebetween. The diaphragm engages at its forward side a springpressed plunger I3! guided in an axial bore in the member H4; and this plunger is constantly urged by a coil spring I32 toward its rearmost position, as shown in Fig. 28. and the plunger I3I engages the operating means for the switch I9. The groove I02 communicates with a passage I33 (Figs. 10 and 2'7), in turn communieating with a transverse valve bore 834 containing a rotary control valve I35, the latter having a manual control handle I88. The valve 135 is of the three-way type and is traversed by passages I3I and I38; and when the valve is in the position shown in Fig. 27 the passages in the valve connect the passage I38 with a passage I39. A passage I40 in the member H4 connects, through a port in the clamped portion of the diaphragm I30, the passage I39 with a passage I4I in the end plate 20 (see also Figs. 25 and 28). The passage I4I communicates with an annular recess I42 (Fig. 28) opening directly into the diaphragm chamber at the rear side of the diaphragm I30. It is accordingly evident that when liquid under pressure is supplied to the feed cylinder to effect forward feed, and the valves and I35 are properly positioned, the diaphragm 530 is actuated to effect operation of the motor switch I9 to start the drill bit rotating motor 54. When the motor switch passage I33 is connected to exhaust by the slide valve 85 through the groove I04 and the exhaust passage I05, the spring I32 acts on the plunger I3I to move the diaphragm rearwardly into the position shown in Fig. 28, thereby to operate the motor switch I9 to stop the motor.

Operation of hydraulic feed and motor controls From the foregoing it will be evident that when the feed control valve 85 is in the position shown in Fig. 15, liquid under pressure may flow from the supply chamber 8| through the slot 91, valve groove 95, ports I09, valve bore I08, ports IIO, valve groove 96 and groove IN to the forward feed passages, while the reverse feed passages are connected to exhaust through slot I00, groove I08, passages I01, groove I04 and exhaust pas sage I05, thereby effecting forward feed of the drill. When the valve 85 is slid forwardly a slight distance, the valve groove 96 is brought out of communication with the slot 98, thereby cutting off the liquid flow to the forward feed passages, while the reverse feed passages remain connected to exhaust, and due to inherent leakage in the fluid line, the forward feeding pressure is reduced to a very low value, removing practically all feeding pressure from the drill bit. When the valve has been moved forwardly to the position shown in Fig. 16, the valve groove 98 is brought into communication with the slot 99, and

liquid under pressure then flows from the supply chamber thrcugh slot 91, valve groove 95, ports I09, valve bore I08, ports IIO, slot 99 and groove I02 to the switch-actuating diaphragm I30, the liquid pressure acting on the diaphragm to move the switch into a position to start the drilling motor. When the slide valve is in this position, the reverse feed passages are still connected to exhaust and the liquid supply to the forward feed passages remains out off by the valve. When the valve 85 is moved forwardly from the position shown in Fig. 16, the valve tion of the valve the recess I42 at the rear of the diaphragm I30 is maintained in communication with the liquid supply 8I. Due to the valve groove 95 being brought into communication with the slot 98, liquid under pressure will flow to the forward feed passages to effect forward feed of the drill while the drilling motor rapidly rotates, thereby to effect the drilling operation. When it is desired to effect retraction of the feed, the slide valve 85 is moved rearward- I ly into the position shown in Fig. 8 and liquid under pressure then flows from the supply chamber through slot 91, valve groove 95, slot I and groove I03 to the reverse feed passages, while the forward feed passages are connected to exhaust through groove IOI, slot 98, the valve bushing bore, groove I04 and exhaust passage I05, thereby to effect reverse feed of the drilling motor. Prior to the initiation of the reverse feed, the motor switch passages are connected to exhaust through groove I02, slot 99, through the valve bushing bore, groove I04 and exhaust passage I05, thereby stopping the drilling motor.

Independent motor control The motor 54 may, if desired, be started by the manual valve I35, independently of the slide valve 85, simply by turning the valve I35 into a position to bring the valve passage I31 into communication with the passage I39 and a passage I43 (Fig. 2'1), the latter communicating with the liquid supply chamber 8|. Communication of the motor switch passage I33 is at that time out off from the passage I39. Liquid under pressure may then flow directly from the supply chamber 8| through the passage I43, valve passage I31, and passage I39 to the diaphragm chamber to actuate the diaphragm I to operate the motor switch 19 to start the motor. To effect stopping of a motor, the valve I35 may be turned into a position to vent the passage I39 through passage I33 by the slide valve 85 through groove I04 and passage I05 to atmosphere. Manual control of the motor switch is necessary during manual feeding of the drill, as will later be explained.

The drilling fluid supply means The means for supplying drilling fluid to the drill bit comprises, as St own in Fig. 21, a passage I44 communicating with the liquid supply chamber BI and with a transverse bore I45 containing a rotary control valve I49, the valve I46 having a manual control handle I41. As shown in Fig. 10, the bores containing the valves I35 and I49 are arranged in axial alinement at the opposite sides of the slide valve 85, and the valve bores at the inner sides of the valves are connected to the fluid exhaust passages I01 through suitable drain ports. The valve I49 is of the two-way type and is traversed by a passage I48 for connecting the passage I44 with a passage I49 (Fig. 21). A passage I50 in the member II4, through a port in the clamped portion in the diaphragm, connects the passage I49 with a groove I5I in the front end face of the head plate 20 (see Fig. 25). A port in the clamped portion of the dia-, phragm connects the groove I5I with a passage I52 (see also Fig. 26) in the member H4, the passage I52 communicating with a bore I53 formed in the member H4 and alined with the rotor shaft 9| at the rest: end of the rotor. The rotor shaft has a, reduced rear end portion projecting rearwardly within the bore I53, as shown in Fig. 26. A washer I54 abuts a split ring seated in an annular groove in the bore walls, and interposed between this washer and a similar washer I55 is a packing I59 sealingly engaging the rotor shaft periphery. A coil spring I51 in the bore I53 acts on the washer I55 for maintaining the packing in tight sealing engagement with the rotor shaft, thereby to prevent leakage of liquid past the shaft to a chamber I58 in the end plate 12. A dirt seal I59 is supported in the bore of the plate 12 and engages a cylindric portion of the member II 4 to provide a seal between the parts. In the event of leakage past the packing I59 to the chamber I58, the latter is connected by a drain passage I90, and a port in the clamped portion of the diaphragm, to a groove I9I formed in the front end face of the head plate 20. The groove IBI is connected to atmosphere through a passage I92. Liquid under pressure may be conducted through the bore I53 through an axial passage I93 in the motor shaft 9| and an alined passage I94 in the adaptor nut 19, as shown in Fig. 6. By the provision of the automatic start and stop means for the motor 54, controlled by the liquid pressure, it is obvious that in the event of failure of the liquid pressure supply durin operation of the drilling motor, the drilling motor is automatically stopped.

Automatic control of feeding pressure supply The torque on the motor 54 automatically regulates the flow of liquid under pressure through the forward-feed passages under the control of the torque-controlled valve means II9 above referred to. As previously described, the motor 54 has limited rotation relative to the control head SI, and secured to the end plate 12 is a torque pin I95 (Figs. 6 and 23) engageable in a groove I99 in a reciprocable valve tappet I91. Tightly pressed in a transverse bore I68 in the control head 5| is a valve sleeve I99 having a Y conical valve seat I10 with which a valve I is engageable. The stem I12 of the valve IN is threadedly secured to the valve tappet as shown in Figs. 22 and 23. The outer end of the bore I68 is closed by a plug I18. The tappet I91 is guided in an alined bore I14 in the control head 3 toward the left as viewed in Figs. 22 and 23,

against the valve sleeve I69. A head I11 of the valve I'II has a sliding fit with a bore I19 in the valve sleeve. A bore I19 at the inner side of the valve seat communicates with the forward feed supply passage II1 through'a port I (see Fig. 22), while a chamber IBI at the opposite side of the valve seat communicates through a port I92 with the forward feed passage H9. The valve stem has a tight sliding fit with the valve bore, but in the event of any leakage past the valve stem to a. bore I83 to the inner end of the valve stem, i. e., the bore which receives the adjacent end of the valve tappet, the bore I83 is connected by a drain groove I94 to the recess in the plug I13, so that any leakage will be conducted from the bore I83 through the drain groove I84 to a vent port in the plug. The pressure of the spring I19 is opposite to the. direction of the torque reaction of the motor 54 and the pressure of the spring is suiiicient to hold the motor stator against rotation during normal full load drilling torque. If the load on the motor exceeds the full load desired, 1. e., if the resistance to motor rotation becomes excessive, the motor stator rotates slightly relative to the control head thereby moving the torque pin and valve tappet to the right as viewed in Figs. 22 and 23. against the pressure of the spring, and as a result the valve is seated, thereby to cut oil the flow of liquid under pressure from the passage II! to the forward feed passage II9. It is accordingly evident that variations inthe 'load on the motor 54, due to variations in the resistance to rotation of the bit, automatically effect control of the forward feeding pressure.

The drilling and breaking means Now referring to the core barrel and core drill bit and the core breaker, it will be noted in Figs. 30 and 31 that a core barrel I85 has a head I86 threadedly connected by a coupling member I81 to the threaded portion of the adaptor nut I6 fixed to the motor rotor shaft 6|. The head member I86 has an axial passage I88 whereby the drilling fluid may be conducted directly from the rotor shaft through the adaptor nut passage and the head and core barrel, to the core bit I69. This core bit is in the form of an annulus armed with spaced cutting sections each consisting of a suitable matrix material set or, less expensive, impregnated, with carbon, desirably bort for cheapness, cutting elements, and is of the type known as a diamond" core bit, and the bit is secured in any suitable manner, as by brazing, to the-forward end of the core barrel I95. The bit, when of the core type, may, due to its construction and mode of attachment to the thin-walled core barrel, drill a very narrow annular hole. Obviously, a plug bit set with cutting elements all over its working face might be used if desired.

When it is desired to break the cores which have been out free peripherally by the core bit, the drilling implement is withdrawn, and a core breaker as shown in Fig. 32 may be employed. This, as illustrated, may comprise a head I90, by means of which attachment to a suitable handling tube or tubular rod I81 may be made, and a sleeve ISI, one side of which is cut away at I92; and the tube is angularly cut ofi at I93 at its forward end, to facilitate insertion of the core breaker within the annular kerf cut by the core bit. Secured, as by welding, along the side of the core breaker tube opposite from the open side thereof is a longitudinally extending rib I94 which thickens that wall of the core breaker tube. The forward end of the core breaker tube is chamfered at I95, further to facilitate insertion of the core breaker tube past the core within the drill hole and to direct the core within the tube. It is evident that when this core breaker tube is inserted in the annular kerf formed by the core bit, the thickened rib portion I94 of the core breaker tube acts laterally on the cylindrical column of rock to apply a breaking pressure thereto, and as the core breaker tube is forced inwardly the core may be broken loose in fragments or completely broken off and received within the core breaker tube; and upon retraction of the tube from the drill hole the core may be removed from the drill hole.

General mode of operation The general mode of operation of the improved drilling apparatus is as follows: The drill may be set up in proper operating position with respect to the working face, with the swivel plate 5 of the drill supporting and guiding means clamped in the saddle mounting of a usual mine column or similar support. The bit-carrying core barrel is then coupled to the adaptor nut I6 at the forward end of the motor shaft, as shown in Fig. l, with the feed cylinder in its retracted position in its guide. Assuming now that a starting hole has been made (this can be done in any suitable manner) and that the drill is alined with this hole the operator will then manipulate the control handle of the feed control valve 85, moving the latter into a position to supply liquid under pressure to the forward feed passages to eifect feeding of the drilling motor forwardly to bring the drill bit within the starting hole at the face and against the bottom of the hole. The control handle is then further manipulated by the operator to move the slide valve forwardly to a position to cut off liquid flow to the forward feed passages, and due to the inherent leakage in the fluid line and the fact that a nonexpansible feeding fluid is used, the forward feeding pressure is reduced to a very low value, substantially removing the, feeding pressure on the drill bit. The operator then adJuststhe control valve I86 to effect a supply of drilling fluid through the hollow motor shaft and adaptor nut to the drill bit. Upon further manipulation of the control handle, the slide valve 85 is moved farther forwardly into a position wherein liquid under pressure flows to the motor switch passages, thereby to effect actuation of the switchoperating diaphragm to cause the switch I9 to start the drilling motor. Upon further manipulation of the control handle, the slide valve 85 is moved still further forwardly into a position again to supply liquid under pressure to the forward feed passages, to effect forward feed of the drilling motor while the drill bit is rapidly rotated. The forward feeding pressure on the drill bit is suflicient to overload the drilling motor in the event of any change in drilling conditions increasing above normal the torque requirements, and in the event of initiation of overloading of the drilling motor, due to an excessive motor torque, the motor torque controlled valve means H8 is actuated to reduce or completely cut 01! the flow of liquid under pressure through the forward feed passages, thereby to slow down or stop the forward feed and preclude serious overload of the motor, and when the motor again operates at its normal load rating, forward feed is automatically resumed or brought back to its designed rate as the case may be. Thus the actual feedin pressure on the drill will always be kept at, or near, as an upper limit, that required to keep the drilling motor working at its normal load rating, though it may obviously be greatly reduced or even entirely removed if conditions of drilling increase in difliculty.

When the feed piston reaches its limit of forward feeding travel and the drilling motor assumes the position indicated in dotted lines in 1, the slide valve 85 is moved rearwardly into a position (Fig. 8) to supply liquid under pressure to the reverse feed passages and the forward feed and motor switch passages are connected to exhaust, thereby stopping the drilling motor and effecting retraction of the feed. The flow of drilling fluid to the drill bit may also be cut ofi by the manual control valve I46. The operator then grasps the portion 46 of the feed s r w operating handle 41 and upon release of the lock 49, 50, the feed screw tube 4| may be rotated relative to the feed nut to effect feeding of the feed cylinder forwardly in its guiding bore on the support I to move the drilling motor from the position shown in Fig. 1 to the full line position shown in Fig. 2. The slide valve 85 is again moved successively into its different operating positions to effect feeding of the drill bit to the bottom of the hole so far formed, then reducing the feeding pressure, starting the drilling motor and then feeding the rapidly rotating drill bit forwardly to effect the drilling operation. Of course, when drilling is effected, the manual control valve 66 is turned into a position to supply drillingfluid to the drill bit. Upon completion of the forward feeding travel of the feed piston, and when the drilling motor assumes the position indicated in dotted lines in Fig. 2, the drilling fluid supply to the drill bit is cut off, the drilling motor is stopped and the feed piston is retracted in the feed cylinder upon the supply of liquid pressure to the latter, and thereafter the feed cylinder is retracted in its guide by the feed screw.

Th drilling motor, if desired, may be fed solely by the feed screw in the following manner. When the drilling motor is in the full line position shown in Fig. 1 with the feed piston and feed cylinder both retracted, the feed screw tube 4| may be rotated by the handle 41 to effect feed of the drilling motor forwardly to bring the drill bit into the starting hole in the working face. The operator may then move the valve I35 to effect actuation of the motor switch 19 to start the drilling. motor, and 'move the valve I45 to supply drillin fluid to the drill bit. Upon continued manual rotation of the feed screw tube 6|, the drilling motor is fed forwardly while the drill bit rapidly rotates, to effect the drilling operation. When the feed cylinder reaches its limit of forward travel in its guide and the drilling motor assumes the dotted line position shown in Fig. 1, the drilling motor is again moved rearwardly by the feed screw tube to the full line retracted position in Fig. l, and liquid under pressure is supplied to the forward feed passages under the control of the slide valve 85 to move the feed piston into its extended position in the feed cylinder, as indicated in dotted lines in Fig.

l. The feed cylinder is then again fed forward- 3,

ly inits guide by the feed screw tube ll to complete the forward feeding operation. The drilling motor is then moved rearwardly by retracting the feed piston within the feed cylinder and moving the feed cylinder rearwardly in its guide by the feed screw. When the drill is retracted by the feed screw, the drilling motor may be stopped by the control valve i 35.

When the coupling of the bit-carrying barrel I85 is released from the adaptor nut 16, the a .drilling motor may be swung laterally on its pivotal mounting on the trunnion support 3 so that the drill. is swung clear of the drill hole, either right or left, as indicated in dotted lines in Fig. 5, so that the core barrel may be moved from the drill hole Without disturbing the drill on its mounting means. This may be accomplished simply by releasing the locking plunger I2 from the locking aperture i3 and swinging the drill support l laterally on the pivot tube 6 relative to the trunnion support 4. This lateral swinging feature of the drill is particularly convenient during the adding of drill rod sections. When using the hydraulic feed mechanism, it will be noted from what has been previously sai that the motor is started under conditions of low or no feeding pressure, and the drill cannot be withdrawn from the hole while the motor is runninga very important feature in view of the highrotative speeds used and the danger from the potential centrifugal forces so available. Also if the water pressure fails the motor will stop before damage to hit or other parts occurs.

When the drill hole is completed, any core which is left attached at the bottom'of the drill hole may be broken off by the core breaker tube l9l, shown in Figs. 32 and 33 and previously described. The broken core may be removed from the drill hole while retained in the core breaker tube or by other means, in an obvious manner.

It may be noted that drilling speeds of a very high order are attained by the uses of motor speeds of the order of 3,600 to 7,200 R. P. M. and feeding pressures as high as 1400 pounds per square inch of projected bit area. These values are not to be assumed as limiting, however, but to be variable with the rock, the bit structure and particularly the bit matrix material, and other conditions.

As a result of this invention, it will be evident that an improved drilling apparatus of the high speed, rotary core type is provided having improved means for rotating the drill bit and improved controlling means for the bit rotation means. It will further be evident that an improved rotary drilling apparatus is provided having automatic feeding means for the drill bit and improved means controlled by the resistance to drill bit rotation for automatically regulating the feeding pressure, whereby the feeding pressure may be relieved from the drill bit in the event of overloading of the drill rotating motor. It will further be seen that an improved drilling apparatus of the rotary type is provided having improved means associated with the hydraulic feeding means, for controlling the starting and stopping of the drilling motor, the starting and stopping means also embodying means for automatically stopping the drilling motor in the event of failure of the liquid pressure supply. It will still further be evident that by the provision of the improved hydraulic feeding means, a high but automatically limited feeding pressure may be applied to the drill bit. Other uses and advantages of the invention will be clearly apparent to those skilled in the art.

While there is in this application described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a drilling apparatus, the combination comprising a drilling motor for actuating a drill bit, said motor having a source of motive power, fluid actuated feeding means for said drilling motor, means distinct from the motive power source for said motor for supplying actuating fluid to said feeding means, and means for automatically stopping said drilling motor in the event of failure of the fluid supply.

2. In a drilling apparatus, the combination comprising a drill bit, a motor for actuating said drill bit to cause the same to effect a drilling operation, said motor including an element which provides the reaction necessary for the actuation of said drill bit, a motor support on which said motor element is mounted for limited movement relative to said support and is normally held againstsaid relative movement but is adapted when said motor is overloaded to move 'relative to said support, feeding means for said drill bit for applying a feeding pressure to the drill bit, and means for controlling the operation of said feeding means, said feed controlling means being operative automatically in accordance with variations in resistance to drilling to preclude application of feeding pressures in excess of desired values to said drill bit, and actuation of said feed controlling means being effected by said motor element upon movement thereof relative to said motor support.

3. A drilling apparatus asclaimed in claim 2, characterized in that said bit actuating motor is a rotary motor and that the reaction element of said motor is mounted on said motor support for limited rotary movement relative to said support.

4. A drilling apparatus as claimed in claim 2, characterized in that said bit actuating motor is adapted. to effect said feed control by a torque controlled valve which is adapted to be operated by said movement of said reaction element of said motor relative to said motor support.

5. A drilling apparatus as claimed in claim 2, characterized in that said bit actuating motor is a rotary motor, that said reaction element of said motor is mounted on said motor support for limited rotary movement relative to said support, and that said control of the feeding means is effected by a torque-controlled valve which is adapted to be operated by said rotary movement of said reaction element relative to said motor support.

6. In a drilling apparatus, the combination I comprising a drill bit, a motor for actuating said drill bit to cause the same to effect a' drilling operation, feeding means for said drill bit for applying a feeding pressure to the drill bit, and means for controlling the operation of said feeding means, said feed controlling means being operative automatically in accordance with variations in the resistance to drilling to preclude application of feeding pressures in excess of desired'values to said drill bit, and said feed controlling means embodying means for controlling the stopping and starting of said feeding means, and said feed controlling means being also operative to control the stopping and starting of said motor.

7. A drilling apparatus as claimed in claim 6, characterized in that the bit, actuating motor is an electric motor and that the stopping of said motor is effected through the intermediary of an electric switch which is adapted to be closed by fluid actuated means controlled by said feed controlling means.

8. In a drilling apparatus, the combination comprising a drill bit, a motor for actuating said drill bit to cause the same to effect a drilling operation, feeding means for said drill bit for applying a feeding pressure to the drill bit, said feeding means being reversible and adapted to feed said drill bit forwardly and rearwardly, and means for controlling the operation of said feeding means, said feed controlling means being operative automatically in accordance with variaations in resistance to drilling to preclude application of feeding pressures in excess of desired values to said drill bit, said feed controlling means embodying means for controlling the stopping and starting of said feeding means and said feed controlling means being also operative to control the stopping and starting of said motor, so that the starting of said motor is effected while said feeding means is stopped, and said feed controlling means also including means for stopping said motor in all cases upon reversal of said feeding means to effect retraction.

9. In a drilling apparatus, the combination comprising a drill bit, a motor for actuating said drill bit to cause the same to effect a drilling operation, feeding means for said drill bit for applying a feeding pressure to the drill bit, said feeding means being reversible and operative to feed said drill bit forwardly and rearwardly, and means for controlling the operation of said feeding means, said feed controlling means being operative automatically in accordance with variations in resistance to drilling to preclude application of feeding pressures in excess of desired values to said drill bit, said feed controlling means embodying means for controlling the stopping and starting of said feeding means and said feed controlling means being also operative to control the stopping and starting of said motor so that the starting of said motor is adapted to be effected while said feeding means is stopped, and said feed controlling means including a fluid actuated motor control device for stopping said bit rotating motor in all cases upon reversal of said feeding means to effect retraction.

10. In a drilling apparatus, the combination comprising a drill bit, a motor for rotating said drill bit, motor control means, reversible means for feeding said drill bit toward and from the work, and means for causing said motor control means always to stop said bit rotating motor whenever said bit feeding means is reversed to effect feed from the work.

11. In a drilling apparatus, the combination comprising a drill bit, a motor for rotating said drill bit, motor control means, means for feeding said drill bit, feed control means, means for supplying a cooling liquid to said drill bit, and means for always automatically arresting feeding of said drill bit whenever failure of the supply of cooling liquid occurs. a

12. In a drilling apparatus, the combination comprising a rotary drill bit, a motor for rotating said drill bit, motor control means, means for supplying a cooling liquid to said drill bit, and means for automatically actuating said motor control means for arresting rotation of said drill bit whenever failure of the supply of cooling liquid to said drill bit occurs.

13. In a drilling apparatus, the combination comprising a drill bit, means for causing said drill bit to drill a hole including feeding means operative upon the supply of energy thereto to apply a feeding pressure to the drill bit, and controlling means automatically controlled by changes in the resistance to drilling for precluding the application of a feeding pressure in excess of a desired value to the drill bit, said controlling means including a reaction member which moves automatically from a normal position upon the resistance to drilling exceeding a.

predetermined value, said controlling means being operative upon said movement of said reaction member to reduce the rate of transmission of energy to said feeding means to preclude such an undesired application of feeding pressure.

14. In a drilling apparatus, the combinationcomprising a drill bit, means for actuating said drill bit including a bit actuating motor, feeding means operative upon the supply of energy thereto to apply a feeding pressure to the drill bit, and controlling means automatically controlled by changes in the resistance to drilling for precluding the application of afeeding pressure in excess of a desired value to the drill bit, said controlling means including a reaction-member operatively associated with said bit actuating motor and which moves automatically from a normal position upon the resistance to drilling exceeding a predetermined value, said controlling means being operative upon said movement of said reaction member to reduce the rate of transmission of energy to said feeding means to preclude such an undesired application of feeding pressure.

15. In a drilling apparatus, the combination comprising a drill bit, means for. causing said drill bit to drill a hole including feeding means operative upon the supply of operating medium thereto to apply a feeding pressure to the drill bit, and controlling means automatically controlled by changes in the resistance to drilling for precluding the application by operation of said feeding means by operating medium supplied thereto of a feeding pressure in excess of a desired value to the drill bit, said controlling means including a reaction member which moves automatically from a normal position upon the resistance to drilling exceeding a predetermined value, said controlling means being actuated, in a direction to preclude such an undesired application of feeding pressure, by movement conse quent upon a predetermined resistance to drilling of said reaction member, said controlling means being operative to preclude such an undesired application of feeding pressure by diminishing the supply of operating medium to said feeding means.

16. In a drilling apparatus, the combination comprising a drill bit, means for actuating said drill bit including a bit actuating motor, feeding means operative upon the supply of operating medium thereto to apply a feeding pressure to the drill bit, and controlling means automatically controlled by changes in the resistance to drilling for precluding the application by operation of said feeding means by operating medium supplied thereto of a feeding pressure in excess of a desired value to the drill bit, said controlling means including a reaction member operatively associated with said bit actuating motor and which moves automatically from a normal position upon the resistance to drilling exceeding a predetermined value, said controlling means being actuated, in a direction to preclude such an undesired application of feeding pressure, by movement consequent upon a predetermined resistance to drilling of said reaction member, said controlling means being operative to preclude such an undesired application of feeding pressure by diminishing the supply of operating medium to said feeding means.

1'7. A drilling apparatus as claimed in claim 13, characterized in that said reaction member is mounted on a support in said apparatus for limited movement with respect thereto, and is normally stationary with respect to said support and is moved relative thereto when the resistance to drilling attains a predetermined value, thereby effecting said actuation of said feed controlling means.

18. A drilling apparatus as claimed in claim 14, characterized in that said bit actuating motor comprises relatively movable parts of which one operates the bit and of which the other comprises said reaction member, a supporting member being provided for said reaction member with respect to which it is movably mounted and with respect to which it is adapted to move when resistance to drilling attains a predetermined value, thereby effecting said actuation of said feed controlling means.

19. A drilling apparatus as claimed in claim 14, characterized in that said bit actuating motor is a rotary motor and said reaction member is mounted for rotary movement relative to its support when the resistance to drilling attains said predetermined value.

20. A drilling apparatus as claimed in claim 15, characterized in that said feeding means is operated by pressure fluid and that said feed controlling means is operative automatically to stop said feeding means by cutting off the fluid supply to said feeding means when the resistance to drilling is above a certain amount.

21. In a drilling apparatus, the combination comprising an actuator for a drilling implement, feeding means for said actuator for applying a feeding pressure to the drilling implement, and means for controlling the operation of said feeding means, said operation controlling means being operative automatically in accordance with variations in the resistance to drilling to preclude application of pressures in excess of desired values to the drilling implement, and said operation-controlling means further embodying means for controlling the stopping and starting of the feeding means, and said operation-controlling means being also operative to effect the starting and stopping of said actuator.

22. A drilling apparatus as claimed in claim 21, characterized in that the starting and stopping of said actuator is effected through the intermediary'of a starting and stopping device which is actuated by fluid actuated means controlled by said operation-controlling means.

23. A drilling apparatus as claimed in claim 15, characterized in that the'feeding means is fluid actuated and includes relatively reciprocable cylinder and piston feeding elements and that manually operated means is associated with said fluid actuated feeding means for feeding said feeding elements into different feeding positions.

24. In a drilling apparatus, the combination comprising a drill bit, a motor for actuating said drill bit, feeding means for said drill bit operable on operating medium supply thereto for applying a feeding pressure to the drill bit, a device for controlling the supply of operating medium to said feeding means, means normally biasing said control device toward a supply effecting position, an element supported for movement under forces produced by resistance to drilling and adapted to move said control device under such forces in an opposite direction, said means normally biasing said control device toward a supply effecting position holding said element stationary until resistance to drilling attains a predetermined value.

25. In a. drilling apparatus, the combination comprising a drill bit, a motor for actuating said drill bit to cause the same to effect a drilling operation, said motor including a rotary element operatively connected to the drill bit for rotating the latter, and a relatively stationary element, means for supporting said relatively stationary element for yielding movement under forces produced during drilling and varying with the ,resistance to drilling, feeding means for the drill bit for applying a feeding pressure to the drill bit, and means for controlling the operation of said feeding means, said feed-controlling means including an element operatively connected with said relatively stationary element and movable by the latter when resistance to drilling attains a predetermined value in a direction to preclude application of feeding pressures in excess of desired values to said drill bit, said feed-controlling means being operative upon movement of said movable element to reduce the rate of transmission of energy to said feeding means to preclude such an undesired application oi feeding pressure.

26. In a drilling apparatus, the combination comprising a drill bit, a motor for actuating said drill bit, motor control means. means for feeding said drill bit, feed control means, and means for supplying a cooling medium to said drill bit, said motor control means dependent upon continued supply of said cooling medium whereby upon failure of cooling mediun. supply interruption of motor operation automatically occurs.

27. In a drilling apparatus, a motor for actuating a drill bit, a motor for feeding the drill bit, controlling means for the supply of operating medium ,to said feeding motor including a device for initiating supp y of and for cutting off said operating medium at the will of the operator and a device automatically controlled by the load on the bit actuating motor for reducing such operating medium supply when such load builds up to a predetermined value, and a device for initiating and cutting off the supply of operating medium to the bit actuating motor having controling medium to said feeding motor including a' device for initiating supply of and for cutting off said operating medium at the will of the operator and a device automatically controlled by the load on the bit actuating motor for reducing such operating medium supply when such load builds up to a predetermined value, and a device for initiating and cutting oif the supply of operating medium to the bit actuating motor having controlling means operable by the operating medium for said feeding motor.

29. In a drilling apparatus, the combination comprising a, drill bit, a motor for actuating said drill bit to cause the same to form a hole, feeding means for said drill bit for applying a feeding pressure to the drill'bit, controlling means for said feeding means operative automatically upon a predetermined increase in the load on said bit actuating motor to reduce the supply of operating medium to said feeding means, and

30. In a drilling apparatus, the combination comprising an actuator for a drilling implement, power operated means for feeding the drilling implement, additional means for feeding the drilling implement, said latter means being adapted to have its operation initiated while the power operated feed is taking place, and means whereby upon the development of an increased resistance to drilling under the action of said additional feeding means automatic interruption of operation of said power operated means is effected, said power operated means during such interruption being maintained ready for automatic resumption of feeding on the resistance to drilling decreasing to a predetermined extent by the discontinuation of feed by said additional feeding means.

31. In a drilling apparatus, the combination comprising an actuator for a drilling implement, power operated means for feeding the drilling implement, manually operated means for feeding the drilling implement, said manually operated means being adapted to have its operation initiated while the power operated feed is taking place, and means whereby upon the development of an increased resistance to drilling under the action of said manually operated means auto- 'matic interruption of operation of said power operated means is effected, said power operated means during such interruption being maintained ready for automatic resumption of feed ing on the resistance to drilling decreasing to a predetermined extent by the discontinuation of manual feed.

32. In a drilling apparatus, the combination comprising a rotary drill bit, a motor for rotating said drill bit, power operated means for feed ing said drill bit, manually operated means for feeding said drill bit,. said manually operated means being adapted to have its operation initiated while the power operated feed is taking place, and means whereby upon the development of an increased resistance to bit r0- tation under the action of said manually operated means automatic interruption of operation of said power operated means is effected, said power operated means during such interruption being maintained ready for automatic resumption of feeding on the resistance to bit rotation decreasing to a predetermined extent by the discontinuation of manual feed.

33. In a drilling apparatus, the combination comprising a rotary drill bit, a motor for rotating said drill bit, fluid operated means for feeding said drill bit, mechanically operated means for feeding said drill bit, said mechanical means being adapted to have its operation initiated while the fluid operated feed is taking place, and means whereby upon the development of an increased resistance to bit rotation under the action of said mechanically operated means automatic interruption of said fluid operated means is effected, said fluid operated means during such interruption being maintained ready for automatic resumption of feeding on the resistance to bit rotation decreasing to a predetermined extent by the discontinuation of feed by said mechanical means.

WIN W. PAGET.

CERTIFICATE OF CORRECTION. Patent No. 2,288,5'41. June 50, 19!;2.

WIN w, PAGE'I'.

It is hereby certified that erroreppears in the printed specification of the above numbered patent requiring correction as follows: Page 1, first column, line 7, fox-"structure" reed --structures--; page 5, first column, line 62, for "supported" read --Journaled--; line 65, for "journaled' read --supported-; and that the said Letters Patent h ld be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and'sealed this 6th day of October, A. D. 1942.

Henry Van Aradale (Sea1) Acting Commissioner of Patents.- 

